Introduction of surveying

1.1   Introduction of Surveying

1.Definition 

Surveying is the sciences and art of determining the relative positions of points on ,above,or below the surface of earth by making direct or indirect measurements of distances, directions, and elevations, and presenting the results in the form of a plan or ma

2.objective(purposes) of surveying 

• To prepare plans and maps of an area showing existing features.
• To set out (lay out) engineering works like roads, railways, bridges, dams, tunnels, buildings, canals — in their correct designed positions.
• To establish boundaries of land parcels (cadastral surveys) for ownership, taxation, and legal purposes.
• To determine areas and volumes (e.g., land area, earthwork quantities, reservoir capacity).
• To provide control points that serve as a reference framework for other surveys and mapping.
• To monitor deformations and movements of structures and the ground over time.

3.primary divisions of surveying 

1. Plane Surveying

• In plane surveying, the earth is assumed to be a flat surface.
• It is generally used for small areas (up to roughly 260 km² )where the curvature of the earth is negligible.
• The curvature of the earth is not considered in calculations.
• It is commonly used for local engineering and construction works.
• It is simple, economical, and requires less precise instruments.
• Lines joining two points are treated as straight lines, plumb lines as parallel, angles as plane angles.

2. Geodetic Surveying

• In geodetic surveying, the earth is considered as a curved surface.
• It is used for large areas (more than 260 km² ) and extensive regions.
• The curvature of the earth is taken into account in measurements and calculations.
• It is mainly used for large-scale mapping, national surveys, and major engineering projects.
• It requires high precision, accurate instruments, and advanced surveying methods.
• Line joining two points is a curved (arc) line; angles are spherical angles.

1.1.1 Basic principal of surveying 

 

1.1.2. Definition of Terms Used in Surveying

1.1.3. Types of Scales and Construction of Graphical Scales

1.1.4. Linear & Angular Measurement

1.1.5. Bearing & Convergence

1.1.6. Types of Error and Correction

1.1.7. Accuracy & Tolerance